Impacted soils occurring from industrial applications and upstream and downstream oilfield activities are becoming an increasing concern. Due to a growing population, public pressure, and environmental awareness, oil companies and industrial firms are exploring quality and cost effective approaches for cleaning up contaminated sites having such impacted soils.
Bioremediation of contaminated soils is a popular and affordable approach for treatment of most soil types and for most contaminates. For example, bio-remediation has been employed to treat hydrocarbon-impacted oilfield well sites. Bioremediation has become increasingly popular as technological advancements have made bioremediation cost-effective, and older treatment methods such as land-filling have fallen out of favor.
While Bio-piles, land farms and introduction of bacterium have been popular approaches to bio-remediation, these passive operations are typically slow-acting and can take years to remediate a contaminated site. These operations also disadvantageously require a large amount of space as soil must be excavated, piled offsite, then have a passive or active aeration system installed thereon.
Other known methods for bioremediation include using an active mixing action that passes soil through air. Such bioremediation methods include use of an Allu™/twister bucket or windrow turners (large rototillers) to contact the contaminated soil. One disadvantage of using Allu™/twister buckets or rototillers is that when the soil is treated, the contaminant vapors are liberated and escape into the air. Rototillers have the further disadvantage of only being able to treat a relatively thin layer of soil at the surface of a contaminated site. Also, both approaches require relatively dry and unfrozen conditions in order to be effective.
Another known method for treating contaminated soils is thermal desorption which actively heats the soil to a temperature which incinerates contaminated particles within the soil. Disadvantageously, this treatment tends to destroy the chemical components and structure of the soil, essentially turning the soil into ash thereby making the soil an unsuitable environment for organic growth.
Recently public pressure and legislation such as the Alberta Energy Board's Directive 58 has created a need to provide an efficient and cost-effective solution for remediating and treating contaminated soil in such a way that does not cause contaminants in the soil to be released into the air.